Securities (Tables)

9 Months Ended

Sep. 30, 2021

Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]

Amortized Cost and Fair Value of Debt Securities Available for Sale

	September 30, 2021								December 31, 2020
			Gross		Gross						Gross		Gross
Securities Available for Sale	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency securities	$	394,069	$	4,822	$	4,169	$	394,722	$	207,365	$	6,289	$	284	$	213,370
Municipal obligations		305,701		13,504		3,178		316,027		309,342		17,536		153		326,725
Residential mortgage-backed securities		3,256,700		39,681		42,988		3,253,393		2,560,249		69,570		8		2,629,811
Commercial mortgage-backed securities		2,838,584		81,615		35,766		2,884,433		2,323,306		135,516		3,288		2,455,534
Collateralized mortgage obligations		133,957		3,628		—		137,585		354,472		7,651		—		362,123
Corporate debt securities		14,500		263		2		14,761		11,500		264		—		11,764
	$	6,943,511	$	143,513	$	86,103	$	7,000,921	$	5,766,234	$	236,826	$	3,733	$	5,999,327

Amortized Cost and Fair Value of Debt Securities Held to Maturity

	September 30, 2021								December 31, 2020
			Gross		Gross						Gross		Gross
Securities Held to Maturity	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
(in thousands)	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
U.S. Treasury and government agency securities	$	—	$	—	$	—	$	—	$	—	$	—	$	—	$	—
Municipal obligations		617,289		39,989		211		657,067		627,019		51,408		2		678,425
Residential mortgage-backed securities		47,330		985		243		48,072		21,951		1,469		—		23,420
Commercial mortgage-backed securities		573,854		36,614		350		610,118		549,686		54,587		—		604,273
Collateralized mortgage obligations		69,228		1,482		—		70,710		158,514		2,949		—		161,463
	$	1,307,701	$	79,070	$	804	$	1,385,967	$	1,357,170	$	110,413	$	2	$	1,467,581

Proceeds from Gross Gains on and Gross Losses on Sale of Securities

The following table presents the proceeds from, gross gain on, and gross losses on sales of securities during the nine months ended September 30, 2021 and 2020.

	Nine Months Ended September 30,
(in thousands)	2021		2020
Proceeds	$	198,681	$	211,919
Gross gains		1,649		1,984
Gross losses		1,316		1,496
Net gain	$	333	$	488

Available for Sale Securities [Member]

Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]

Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

Debt Securities Available for Sale	Amortized		Fair
(in thousands)	Cost		Value
Due in one year or less	$	2,290	$	2,294
Due after one year through five years		636,212		670,865
Due after five years through ten years		2,805,443		2,839,375
Due after ten years		3,499,566		3,488,387
Total available for sale debt securities	$	6,943,511	$	7,000,921

Securities with Unrealized Losses

Available for Sale
September 30, 2021	Losses < 12 months				Losses 12 months or >				Total
(in thousands)	Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses		Fair Value		Gross Unrealized Losses
U.S. Treasury and government agency securities	$	199,451	$	2,712	$	32,489	$	1,457	$	231,940	$	4,169
Municipal obligations		43,297		2,098		25,243		1,080		68,540		3,178
Residential mortgage-backed securities		2,097,625		42,984		704		4		2,098,329		42,988
Commercial mortgage-backed securities		856,462		22,196		294,972		13,570		1,151,434		35,766
Collateralized mortgage obligations		—		—		—		—		—		—
Corporate debt securities		2,998		2		—		—		2,998		2
	$	3,199,833	$	69,992	$	353,408	$	16,111	$	3,553,241	$	86,103

Available for Sale
December 31, 2020	Losses < 12 months				Losses 12 months or >				Total
			Gross				Gross					Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	35,845		284	$	—	$	—	$	35,845	$	284
Municipal obligations		30,170		153		—		—		30,170		153
Residential mortgage-backed securities		530		2		760		6		1,290		8
Commercial mortgage-backed securities		446,190		3,288		—		—		446,190		3,288
Collateralized mortgage obligations		70		—		—		—		70		—
Corporate debt securities		2,000		—		—		—		2,000		—
	$	514,805	$	3,727	$	760	$	6	$	515,565	$	3,733

Held-to-maturity Securities [Member]

Schedule Of Gain Loss On Investments Including Marketable Securities And Investments Held At Cost Income Statement Reported Amounts Summary [Line Items]

Amortized Cost and Fair Value of Debt Securities by Contractual Maturity

Debt Securities Held to Maturity	Amortized		Fair
(in thousands)	Cost		Value
Due in one year or less	$	11,226	$	11,371
Due after one year through five years		336,328		354,897
Due after five years through ten years		548,812		587,548
Due after ten years		411,335		432,151
Total held to maturity securities	$	1,307,701	$	1,385,967

Securities with Unrealized Losses

Held to maturity
September 30, 2021	Losses < 12 months				Losses 12 months or >				Total
			Gross				Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	—	$	—	$	—	$	—	$	—	$	—
Municipal obligations		7,789		211		190		—		7,979		211
Residential mortgage-backed securities		7,821		243		—		—		7,821		243
Commercial mortgage-backed securities		11,960		350		—		—		11,960		350
Collateralized mortgage obligations		291		—		—		—		291		—
	$	27,861	$	804	$	190	$	—	$	28,051	$	804

Held to maturity
December 31, 2020	Losses < 12 months				Losses 12 months or >				Total
			Gross					Gross				Gross
	Fair		Unrealized		Fair		Unrealized		Fair		Unrealized
(in thousands)	Value		Losses		Value		Losses		Value		Losses
U.S. Treasury and government agency securities	$	—	$	—	$	—	$	—	$	—	$	—
Municipal obligations		—		—		2,381		2		2,381		2
Residential mortgage-backed securities		—		—		—		—		—		—
Commercial mortgage-backed securities		—		—		—		—		—		—
Collateralized mortgage obligations		—		—		—		—		—		—
	$	—	$	—	$	2,381	$	2	$	2,381	$	2